While I won't hack or rng(I keep trying to figure it out but it is so confusing to me, even with instructions), I fail to see why someone shouldn't hack in a Pokemon for reasons beyond breeding. No do I see any point in telling people how to play the game I'm going to believe they paid for(and for those who didn't, you have even less reasons to tell them not to hack in Pokemon to alter their play style). I prefer earning it, yes, but having to do waaaaay too much to earn something you only intend to use a handful of times dampens the creative process. Limitations are meant to be worked around, and overcome. I'm not saying hacking enhances fun, but it might allow some to approach things from a more unique angle than one might usually do. I prefer to experiment within my limitations, and these games are perfect for that, as there are so many combinations you can achieve, you never know what to expect really.
Perhaps I might Pokegen or RNG someday, but for now, I have little reason to, as I have a wide array of options to try out left before me. Who knows, I might stumble across some workaround no one else had, however unlikely.
I breed and train myself. I care about IVs so I breed enough for a variety to choose the best IVs from, but I don't care enough nor do I have the patience to continuously breed for multiple perfect IV's.
I hack to get perfect parents, or make certain wild Pokemon (usually legendaries) have the right IVs. Outside of that, I level grind and EV train the normal way, since I find those grinds, where you can make clear progress that is not at all based on luck, more fun than the grind for half decent IVs and a good nature, which until the most recent games have been almost entirely luck based.